rbenv-vars - Rails app is not reading them. How do they get loaded?

[Jay Godse]

I am trying to deploy a Ruby 2.2 / Rails 4.2 application from a project I inherited, and rbenv-vars is used (along with rbenv). When I try to start the Puma service, I can tell that the rbenv variables aren't getting loaded because RAILS_ENV is not set, and database.yml doesn't read the environment and uses defaults.

What do I have to do to get Ruby to load rbenv-vars to load the environment variables?